1. Field of Invention
The present invention relates generally to pressure washer apparatus, and more particularly, to methods and apparatus for separating and containing lower-density or lightweight contaminants from contaminated washing fluids for use in the pressure washing apparatus.
2. Description of the Relevant Art
Contamination of the environment by man-made substances has been considered a serious world-wide problem. Recently, concern about contamination of earth, air, and groundwater by oil, toxic chemicals, and other hazardous wastes has expanded beyond large-scale industry to encompass the activities of many small businesses including automobile service stations, and many others. Both government regulations and social outcry have placed tremendous pressure on these businesses to avoid discharging hazardous wastes into the environment in the course of ordinary business activities.
Many businesses partake in activities which are likely to produce waste which may be harmful to the environment. For example, in an automobile service station, washing or steam-cleaning auto parts, e.g., an automobile engine, often causes engine oil, gasoline, and other chemicals to enter a storm drain system, or other waterways, thereby leading to the potential contamination of groundwater. In addition, those who service remotely located equipment generally have a need to wash the equipment without discharging hazardous waste into the environment. By way of example, persons who service roof-mounted air conditioners that contain lubricating petrochemicals, trapped pollutants, or other chemicals are not permitted to wash the equipment in a manner that could cause chemicals to run off the roof and into the surrounding environment.
To address these concerns, portable, closed-loop pressure washing equipment has become widely available which may recover oil, chemicals, and other hazardous materials from an object which is being washed. These pressure wash assemblies may efficiently recirculate, heat, and repeatedly filter a washing agent to minimize the quantity of waste material produced during a washing process. Typical of such systems are disclosed in U.S. Pat. Nos.: 5,673,715; 5,785,067 and 5,803,982, incorporated herein by reference.
These zero-discharge, closed-loop wash apparatus typically deploy a multi-step contaminant removal process designed to independently separate the heavier weight or higher density contaminants, relative the density of the washing fluid, as well as separate the lighter weight or lower density contaminants from the washing agent. A collection basin of the wash apparatus, for example, may be configured to remove the heavier weight contaminants through the application of filtration baskets or through sediment settling of the coarser heavier sediments along the bottom of the collection basin. The medium weight or medium density contaminants, on the other hand, may remain suspended in the washing fluid, where they may be removed by filtration through micron filters or the like. In some designs, a succession of micron filters may be used to remove successively smaller particulates and molecules from the washing agent.
The lightweight contaminants, such as gasoline, oils and lightweight chemicals, are caused to gravitate toward and float on the surface of the washing fluid. Eventually, these contaminants accumulate at the surface of the washing agent, and require periodic removal. Some conventional assemblies may effectively, or at least partially, filter out these contaminants without any additional componentry. However, these hazardous wastes are typically either not isolated, or are not consistently or efficiently filtered out of the washing fluid.
One technique for removal of these highly abundant forms of contaminant is a belt skimming device. As illustrated in FIG. 1, the belt skimmer device 10 typically includes a belt 11 which is capable of extracting the lightweight contaminants, using selective surface tension properties, and transporting them to a holding compartment 12. The efficiency and maximal removal rate of the belt skimmer 11 is thus dependent on contaminant abundance as well as surface tension properties of the low density contaminant 13, the washing fluid 15 and the belt 11. While the belt skimmer device 10 may be efficient in the presence of abundant contaminants, during low contaminant levels, the washing fluid 15 tends to cling to the belt 11. This disadvantageously compromises efficiency of the belt skimmer device 10 and additionally removes washing fluid from the closed pressure washing system. Further, the presence of a motor increases the maintenance and power consumption costs, as well as increasing the potential for igniting flammable contaminants an electrical shock.
Another conventional low-density contaminant removal system is an absorbent sock system (not shown) which filters the contaminated washing fluid through a plurality of absorbent socks whose absorption properties are used to remove contaminants. The primary drawback of this approach, however, is that socks introduce a new residual hazardous waste product to the environment. Moreover, although this removal system is mechanically less complex, the contaminant removal is disadvantageously restricted to only liquid contaminants. Another disadvantage to this system is that separate chambers are required for the absorbent socks. Ultimately, this increases the fabrication and costs, as well as increasing maintenance. Finally, the absorbent sock system frequently restricts flow of the washing fluid which in turn reduces output performance.
Yet another conventional, low-density contaminant removal device are chemical fluculation systems which in effect encapsulate the targeted contaminants. While these systems are capable of solid contaminant removal, the encapsulating substance must be manually supplied in batches. Accordingly, this task is relatively laborious, time consuming and requires active monitoring and maintenance. Further, the chemicals must be added in adequate proportions based on contaminant influx and thus are not efficient in a continuously variable cleansing application. Further, the high cost of these chemicals may not be comfortable for many operations and small businesses which may compromise their continuous application and effectiveness.
In view of the foregoing, it is apparent that improved low-density contaminant removal techniques for a pressure washer are desirable.